Some sensor/digitizer problems we have had in the past.
Problem:The sensor was off for around 6 month due do power problems. The spectrum of BHZ has sometimes an pulse which occur the straight lines in the spectrum. Sensortype: Trillium 120Solution:After unplug/plug the connector for several times the signal was good again. Looks like it was only an connection problem. We have seen similar problems also at other stations